In the exponential growth model equation
\( \displaystyle \frac{dN}{dt} = rN \)
‘N’ stands for :
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → Population size
In the exponential growth equation, N is the population size, r is the intrinsic rate of natural increase, and dN/dt is the change in N per unit time.
Option (1) Population size — Correct. In the exponential growth equation dN/dt = rN, N is the population size (density), r is the intrinsic rate of natural increase, and dN/dt is the rate of change of population size.
Option (2) Number of births — Incorrect. Births enter the equation through the birth rate b, which is part of r.
Option (3) Number of deaths — Incorrect. Deaths enter through the death rate d; r = b − d.
Option (4) Difference between births and deaths per unit time — Incorrect. That is close to what dN/dt (or r, per individual) describes, not N.